Traversing roll type extruder

ABSTRACT

The present invention is an improved pellet mill die and roller assembly wherein the roll assembly is provided with removable end guides to prevent material from being squeezed out from between the die surface and the ends of the working portion of the roll.

United States Patent [191 Alessio [451 July 3,1973

[ TRAVERSING ROLL TYPE EXTRUDER [75] Inventor: Aldo M. Alessio, Novato, Calif.

[73] Assignee: California Pellet Mill Company, San

Francisco, Calif.

[22] Filed: July 23, 1971 [2]] Appl, No.: 165,659

[52] US. Cl. 425/192, 425/331 [51] Int. Cl B28b 3/20 [58] Field of Search 425/331, 363, 192,

425/DlG. 40

[56] References Cited UNITED STATES PATENTS 3,144,840 8/1964 Crane 425/331 3,467,031 9/1969 Hafliger 425/331 Primary ExaminerH. A. Kilby, Jr. Attorney-Bruce & McCoy 5 7 1 ABSTRACT The present invention'is an improved pellet mill die and roller assembly wherein the roll assembly is provided with removable end guides to prevent material from being squeezed out from between the die surface and the ends of the working portion of the roll.

5 Claims, 1 Drawing Figure PATENTEUJUL 3m 3.743462 INVENTOR. ALDO M. ALESSIO TRAVERSING ROLL TYPE EXTRUDER BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to pellet mill dies and extrusion rolls and, more particularly, to a roll and die for the pelleting of material and which cooperate to hold the material being pelleted from squeezing out from under the ends of the extrusion roll.

2. Description of the Prior Art In pellet mills, the mixture of material to be pelleted is normallyfed to a die having a plurality of extrusion holes therethrough. An extrusion means, such as one or more extrusion rolls, travels over the compression side of the die and squeezes the material between the die and the rolls. This movement forces the material through the die holes. As the material emerges from the discharge side of the die, the extrusions are severed to produce pellets.

In flat surface dies which are traversed by an extrusion roll, material escapes from both ends of the roll with the result that more material will be extruded through the holes located in the central region of the die than toward the outer edges of the die. Under these conditions, the die will wear at a faster rate at the center thereof. Consequently, the die will wear concave and become useless while there is stilla great deal of usable life left in the outer edge regions.

A further problem connected with the operation of pellet mills is in obtaining uniform extrusion results,

through each of the extrusion holes. Invariably, the extrusion of the material through the die holes located at the outer edges of the operating area of the die is not as uniform and efficient as with the central die holes which are traversed by the center of the extrusion roll. This results in the outer holes forming shorter and less dense pellets.

One means of overcoming the irregular wear of the die and production of nonuniform pellets, is set forth in U. S. Pat. No. 2,652,007 for DIE BOWL ASSEM- BLY by Edgar N. Meakin, issued Sept. 15, 1953. This patent relates to a die bowl assembly for a ring die through which material is extruded by a pair of compression rollers. The assembly has an inwardly sloping circular bowl which is suspended to engage and support the outer edge of the die. The operating area of the die which is traversed by the rollers is provided with a pair of low walls rising from the compression surface of the die and bordering along the inner and outer peripheries of the extrusion roller path. These walls are formed of metal rings which are clamped or rabbeted in position and fastened to the die by machine screws or bolts whereby they can be readily replaced. The rings overhang the inner periphery of thed ie and are made from a material which can withstand the abrasive action of the extrusion material. I

The rings described in that patent, however, are only useful in the die bowl type of pellet mill as described and do not contemplate the construction of the present invention which has a fixed circular or annular die with charged side with a plurality of die holes extending OBJECTS OF THE INVENTION It is therefore an important object of the invention to provide an improved pellet mill die and extrusion roll.

It is another object of the present invention to provide an improved pellet mill die and extrusion roll for I providing an extended useful life of the die and roller.

It is a further object of the instant invention to provide an improved pellet mill die and extrusion roll having a greater and more uniform extrusion pellet output.

It is still another object of the present invention to provide an improved pellet mill roll and die having more uniform wear characteristics over the compression side of the die.

And it is yet a still further object of the present invention to provide an improved pellet mill roll and die having replaceable holdingv means to resist the squeezing out of extruded material at the ends of the extrusion roll.

Additional objects of the invention will be brought out in the following description of a preferred embodiment of the same taken in conjunction with the accompanying drawing.

DESCRIPTION OF THE DRAWING The drawing is a view partly in cross section, through one form of pellet mill die, utilizing the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT In general, the problem of nonuniform wear and nonuniform production of conventional dies is solved in accordance with the present invention by providing a holding means at the ends of the roll. The holding means coacts with the die to prevent material from being squeezed out from between the roll and the die during extrusion. This retention of the material will increase the operating efficiency of the die and provide more uniform wear thereof.

Referring to the drawing for details of the invention, shown therein is a die 11, which may be either annular or circular in form, having a compression side 13 and a discharge side 15 with a plurality of circular die holes 17 preferably arranged in rows and extending through the die from the compression side to the discharge side..

' If in rows the holes will preferably be staggered with rean extrusion roller moving across the working surface thereof.

SUMMARY OF THE INVENTION spect to the holes in adjacent rows in accordance with conventional practice.

Provided in cooperation with the die are one or more extrusion rolls 21, each of which spans the rows of die holes and traverses the compression side of the die. In

' this manner, material deposited on the surface of the die will be extruded through the die holes and expelled from the discharge side of the die. As the extrusions emerge they are periodically severed into pellets.

In accordance with the preferred manner of accomplishing the objects of the present invention, the roll 21 is provided with a flange formed by an annular ring member 23 on at least one end and preferably at each end thereof. Each of the ring members is of such a diameter that it extends outwardly from the roll whereby its circumference 24 extends into a relief channel or slot 25 formed in the compression surface of the die at each edge of the extrusion roller path on either side of the die holes 17. The coaction between the circumference 24 of the annular rings 23 and the bottom of the relief channels 25 is such that the roll 21 is still able to turn with respect to the die 11, but will prevent the passage of material therebetween.

The ring members are preferably constructed of material which is best capable of withstanding the abrasive action of the extrusion material to be extruded and yet may be discarded and replaced with similar rings when worn.

The rings may be mounted on the roll 21, such as by holding members 27 having a plurality of cap screws 29 which pass through holes formed in the holding members and into threaded bores formed at the ends of the roll. As shown, each of the holding members 27 is preferably circular, with a raised projecting cylindrical internal portion 31 of substantially the same diameter as the central openings formed in the annular rings 23. This enables each of the annular rings to be accurately aligned and then clamped between the radially extending surface 33 of its respective holding member and the adjacent end of the roll.

With annular rings 23 secured at both ends of the roll 21 and projecting into the relief channels 25 of either side of the die holes 17, any material which normally has a tendency to be squeezed out from between the die surface and the ends of the roll will be restrained by the ring members. Furthermore, the coaction of the circumference 24 of the ring members with the bottom surface of the relief channels 25 effects the proper spacing of the roller from the die and insures scaling to prevent any material from passing thereby. This resistance to the squeezing of the material out from between the ends of the roll and the die thereby causes the die holes on both edges of the roll path to be subjected to the same load causing even wearing of the die. Furthermore, all material fed to the roll and die will be compacted and extruded, thereby saving on waste and producing pellets of even size and density throughout thedie.

One advantage of the present invention is provided by the fact that ordinary dies and rolls now used in present pellet mills may be easily modified by attaching annular ring members to the ends of the rolls and replacing the existing die with a grooved one This may be accomplished by merely providing threaded holes in the ends oftthe rolls and fixing annular rings thereto by means of holding members and capscrews. This simple y conversion of presently utilized dies and roll assemblies will increase the efficiency and life of known extrusion mills.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood, that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

What is claimed is:-

I. In combination, a pellet mill die having a compression side, and a discharge side with a pluraity of die holes extending from said compression side to said discharge side, a pair of relief channels formed in the compression side on each side of said die holes, an extrusion roll disposed in extrusion relationship to and adapted for movement over said compression side of said die, and holding means secured to said roll and coacting with said relief channels to retain material squeezed laterally from between said roll and said die when said roll is moved over said die.

2. The pellet mill die of claim 1 wherein said holding means comprises flanges secured to each end of said roll which engage and coact with said relief channels to prevent material from being squeezed from either end of said roll.

3. The pellet mill die of claim 2 wherein said flanges comprise annular rings which are removably secured to said roll so as to be capable of being replaced without requiring said roll and said die assembly to be disassembled.

4. The pellet mill die of claim 3 including holding members which are removably secured to the ends of said extrusion roll and have projecting cylindrical central portions and radially extending surfaces for clamping said annular rings to said roll ends between said radially extending surfaces and said ends.

5. In combination, a pellet mill die having a compression side and a discharge side with a plurality of die holes extending from said compression side to said discharge side, a pair of channels formed in the compression side on each side of said die holes,

an extrusion roll disposed in extrusion relationship to and adapted for movement over said compression side of said die,

an annular holding ring removably secured at each end of said roll coacting with the bottoms of said relief channels, and

holding members which are removably secured to the ends of said extrusion roll and have projecting cylindrical central portions for insertion into said annular rings, and radially extending surfaces to thereby clamp said annular rings into which they are inserted to the roll ends between said surfaces and said ends to thereby prevent material from being squeezed from between saidroll and said die when said roll is moved over said die.

a, a a a c 

1. In combination, a pellet mill die having a compression side, and a discharge side with a plurality of die holes extending from said compression side to said discharge side, a pair of relief channels formed in the compression side on each side of said die holes, an extrusion roll disposed in extrusion relationship to and adapted for movement over said compression side of said die, and holding means secured to said roll and coacting with said relief channels to retain material squeezed laterally from between said roll and said die when said roll is moved over said die.
 2. The pellet mill die of claim 1 wherein said holding means comprises flanges secured to each end of said roll which engage and coact with said relief channels to prevent material from being squeezed from either end of said roll.
 3. The pellet mill die of claim 2 wherein said flanges comprise annular rings which are removably secured to said roll so as to be capable of being replaced without requiring said roll and said die assembly to be disassembled.
 4. The pellet mill die of claim 3 including holding members which are removably secured to the ends of said extrusion roll and have projecting cylindrical central portions and radially extending surfaces for clamping said annular rings to said roll ends between said radially extending surfaces and said ends.
 5. In combination, a pellet mill die having a compression side and a discharge side with a plurality of die holes extending from said compression side to said discharge side, a pair of channels formed in the compression side on each side of said die holes, an eXtrusion roll disposed in extrusion relationship to and adapted for movement over said compression side of said die, an annular holding ring removably secured at each end of said roll coacting with the bottoms of said relief channels, and holding members which are removably secured to the ends of said extrusion roll and have projecting cylindrical central portions for insertion into said annular rings, and radially extending surfaces to thereby clamp said annular rings into which they are inserted to the roll ends between said surfaces and said ends to thereby prevent material from being squeezed from between said roll and said die when said roll is moved over said die. 